From Fit to Fat in 14 Days?

Sloth works fast: It only takes two weeks of inactivity—at most—to see significant changes in metabolism and fitness, according to a review published online in the Journal of Applied Physiology.

One study, for example, looked at healthy guys who walked about 10,000 steps/day and then reduced it to 1,500 steps/day, while maintaining a normal diet. The results: A 7 percent increase in belly fat—after just 14 days!—plus a 7 percent decrease in aerobic capacity (VO2max), reduced muscle strength, and worsened insulin sensitivity.

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It only took three days of reduced activity for the team to notice increased levels of blood glucose post-meals, which over time puts guys at an increased risk for developing type 2 diabetes and heart disease.

Disclaimer: There are plenty of benefits of taking a day off of training if you need it. (Lifting every other day is even one of our Top 10 Muscle-Building Tips.) Keep in mind that these studies focused specifically on non-exercise activity—walking around the block, to the bus stop, or just to a coworker’s desk.

And don’t think you’re off the hook just because you work out: “There is new epidemiological evidence suggesting that even in those who regularly exercise, increased sitting time is linked to increased risk of disease,” says lead author John P. Thyfault, Ph.D., assistant professor at the University of Missouri. “Get up every 15 to 20 minutes and move around, otherwise the skeletal muscles become completely inactive for prolonged periods of time which initiates biochemical changes that contribute to insulin resistance and elevated blood glucose.”

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